Control of alternating-current motors.



H. MAXWELL.

CONTROL OF ALTERNATING CURRENT MOTORS.

APPLICATION FILED PERM. 19061 318,6888 Patented Apr. 20, 1909.

WiTNESSES I \NVENTEI'R.

- HuwAD MAXWELL. WW

Unrr n STATES? PATENT onnron.

nowARn MAX ELL, OF SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEoTmo.

COMPANY, A CORPORATION or NEW YORK.

I common or ALTERNATING-GURREQNT MOTORS.-

. i I Specification of Iietters Patent. Patented April 20, 1909; I 1Application filed February 14, 1906. Serial No. 301,029.

To all whom it may concern: these 'deyices out of circuit directly u onthe "Re it-known that I, HOWARD MAXWELL, amotor attaining the runningspeed, t ley are citizen of v the iUnited States, residing at out outgradually step by step, and for this Schenectady, in the county ofSchenectady u ose they are so arranged that they can and State of'NewfYork, have-invented cerhe t h tainlnewand useful Improvements in Gen-lline. The resistance and reactance are di-. tr'eloFAlternating-GurrentMotors, of which} videdv into sections and provided with conthefollowing is a specification. tacts adapted to be engaged by the pivotedThis invention relates to the control off controlling arm, as is commonin starting alternating-current motors and has for its; rheostats. Theresistance and rfeactanee are object the provision of a device forstarting inseries with different-phases of the motor Inotors'of theinduction type and bringing and are concentrically arranged so that thethem up torunning speed in a reliable, safe sections of each are cutsimultaneously and andefiicient manner. pro ortionately so as tomaintain the roper 15 More specifically, my invention relates to depasing eiiect during starting, there y sethe starting of single-phasemotors of the incuring a good torque from rest to full speed. 'ductiontype. This type of motor, as is In the cutting out of the reactance stepby WVGll-dfllOVEll, not start from-rest without .step, it isundesirable, and, in fact, somethe employment of special startingdevices, what dangerous to short-circuit, a section or 20 such as.auxiliary starting windings, or sectionsthereof, and I, therefore,provide phase splitting devices connected. in the means whereby thecontrolling element motor circuit, or both. Devices of this charmakes aquick break with the .contact. and acter are designed to be in circuitonly for a moves quickly to the next contact, the enshort period, duringwhich the motor is being tire circuit being broken at each step. The

5 brought upto synchronism, and if left in controlling arm is ivoted ina manner simicircuit too long will become overheated. 'lar to the controg, lever of a starting. Meanshave, therefore, been employed for rheostatand is biased to the OE position, changing the connectionsfso as to cutout while a no voltage magnet retains t in the these auxiliary startingdevices} In the running position.

30 case of motors with threegphase windings Inthe accompanying drawing,Ihave illuswhich are to be operat'edon single-phase trated adeviceembodyin my invention, but current, it has been the practice to use a itshouldbe understood t at this is illustratriple-pole double-throwswitch, which, when tive merely and that many changes and vathrovtn oneposition, starts the motor riations may be'made by those skilled in the5 with its windings Y connected, with the adart without departing fromthe spirit of my dition iii a resistance reactance device for invention.producing a displaced phase at the third .Referring to the drawing, 1representsan terminal}? After the motor has been brought insulating baseof slate, or soapstone, having up. to speed, the switch is thrown. intothe mounted thereon a series of contacts 2 and 3 0 oppositeposition,Which-cuts out the resistarranged concentrically about 4 as a center.9,5- ance-reactance device and places the motor The contacts 2 formterminals for a series of with its windings delta connected directlyresistances '5, while the contacts 3 are simion the line. With anarrangement of this larlyoonnected with the sections-of a reactcharacterthereis nothing to prevent the opance 6. The controllinglever 7, pivotedat a +5 erator from throwing the. switch into the 4, is adapted tosweepover and successively starting position and leaving it there, or engagetecontacts2 and 3. The insulating from throwing the switch into therunning segments 8 and 9 are arranged to engage the position directly,Without passing through starting arm when in initia position, and an.the starting position. Moreover, this type insulat1ng segment 10 isarranged adjacent 50' of device provides no means of throwingt ie aswitch into theoif position on failure of'vol- 'forth. Inorder toprevent the short-circuit tage, so es to protect the'motor upon the re;ing of any oi the sections of the reaotance 6, turn of ve'ltageto theline. In carlying ,oiit, the contacts S-are separated some distance v myinventionfi, likewise, provide a resist: from each otherland theinsulating contacts .55 ance-reactance device, butinstead of'ciitting 11are set between them, so as to form a 110 us out out withoutshort-circuiting the so to the contacts 3 for purposes hereinafter setthe well-known devices for this purpose.

plish'ed' is no part of my the drawin I haveillustrated one method,by'which t is may be carried out, but the particular means whereby thisis accomnventlon and may e varied at will.

i f A ratchet Wheel 12 is rotatably mounted oripivot' l and is preventedfrom movement i 17 at '18 by means of a spring 19. A pawl,

in a clockwise direction by means of the pawl IS piVoted; at 14 "andhaving a bearing face 13, the contour of which corresponds with that ofthe tooth engages the beveled face 'l l of the teeth to act as a stop.The

is'prin 15 has one endsecured to the awl 13 and t e opposite end securedto the ever 7,

the intermediate portionbein wound around thepivot 4, thus forcing theever and pawl toward each other. The'controlling lever 7 comprises twoportions; the operating arm proper, provided with the handle 16; and

the contact portion 17; both of which are independently pivoted at 4. fThe end of the operating arm opposite the handle 16 is 'yieldinglyconnected with the contact arm *or'b olt, 20, having a slot 21, isarrangedto receive the whereby the ins 22 fixed in the arm 17 .holt mayslide longitudinally of the arm. A pin 23, secured to the bolt, enages adiagonal slot 24 in the arm 7. The

vl ower end 0t thebolt 20 is'made in the shape of a tooth to engage theteeth of the ratchet wheel 12 to lock the same. It willbe seen that whenthe handle 16 is moved in a clockwise direction the pin 23 will beforced out-' ward from the center 4, carrying with it the bolt 20.. lThehandle 16, however, is moved some distancelrom the arm 17 before thebolt finally disengages from the teeth of the wheel, and a tension isthereby put on the spring 19. The distance which the handle 16 moveswhile the bolt ismoving out. from the t0 th is substantially thedistance between the contact studs, so that when the bolt finallyreleases the arm 17 quickly moves in response to the tension of thespring 19 to a positionon the next contact. The arm 17 likewise carriesa brush 17 for engaging the contacts 2,. but in this case the contacts.are'short-circulted, as is usual in rheostat practice. A no voltagerelease magnet 25 is connected in-circuit with the motor either acrossthe main base or across one of the other. phases of t e motor, and

, controls an armature 26 pivoted at 27, having a slot 28 adapted toengage a pin 29 on the arm 17 whe'n the latter is moved to the runningposition," the armaturebeing normally pressed away from the magnet bytwo of the contacts3, and as the means of the compiession -spring 30. Astop 31 forms an abutment for the controlling arm when in the offposition.

The operation of my device will beclearly understood from the fore oingdescription.

In the off position the paw 13 rests upon the oint of one of the teethof wheel 12 and the rushes 11 and 17- engage the insulation segments 8and 9.. When it-is desired to start the motorthe handle 16 is moved tothe left. Wheel 12 and arm 17 both move with the handle until the face13' oi awl 13 en ages the adjacent tooth. This ocks the w eel andlikewise arm 17 through bolt 20. The handle ismoved along, however,putting a tension on the spring 19 and gradu-. ally sliding the bolt 20out from en agement with the teeth of the wheel 12. hen the arm is moveda distance e ual to the distance between contacts, the olt 20 releasesthe arm 17, which snaps over to the next stud. In this manner thecontacts are passed over,- radually cutting out the resistance 5 an theresistance 6 proportion- .ately. The brush 11', which engages thecontacts 3, finally passes on to the 'msulating segment 10, breaking thereactance circuit while the brush which engages the contacts 2 completesthe circuitthrough the last. resistance contact. The urpose of breakingthe reactance circuit be ore it is entirely cutout is to avoidshort-circuiting phase'B of the motor winding, which would occur if bothresistance and reactance were reduced to a very small quantit beforeopening the circuit of either.

ai ure of voltage the'armature 26 is released and the arm flies back inresponse to the tension of the spring 15, carrying withit the wheel 12,which ratchets over pawl 13.

The direction ofg'the current is as follows: When the arm is moved ontothe first oithe starting contacts current passes from the line throughthe conductor 32 to ivot 4. thence through the arm 17 to the resistance5 and reactance 6. From the resistance 5 current passes throughconductor 33 to one termina of the three-phase winding of the motor M at34, thence through the motor winding to the line L at 35. A branch fromthe reactance 6 passes through conductor 36-, to a second motor terminalat 37 thence through the motor winding to the hue L aten the arm reachesthe running pos tion, that is, in engagement with 35. A phasedisplacement of the current is thus roduced in the three portions A,Band C of t e threehase winding which starts the motor, and w enthe'motor is finally in running condition the reactance circuit isbroken at 10, as above described, and the motorisconnectedas asinglebase motor directly across the line. It will he seen that theresistance and reactance are connected in series with.

' out of circuit stepy While-I have described my invention in connectionwith a particular'ty'pe of mechanism and likewise a particular type ofmotor, it should be understood thatI do not limit my invention as to themechanism employed nor to the winding-arran ement of the motor, exceptas it is limited by the claims annexed to and forming a part of thisapplicat1on.

What I claim as new and desire to secure by Letters Patent of theUnitedStates, is,

, 1. In combination with a single-phase source of current, an inductionmotor having a three-phase winding, devices having differentimpedancerea tors connected inseries with two phases of the motor winding, andmeans for simultaneously varying the impedance of ,-s aid devices ste bystep. f

- 2. In. combination with a single' phase source of current, aninduction motor having a three-phase winding, aresistanceand a reactanceconnected respectively in series with two phases of the motor winding,and means for simultaneously reducing the, impedance thereof step bystep.

1 source of 3-. The combination with a single-phase current and aninduction .motor having a three-phase winding, of means for starting thesaid -moto'r com rising a resistance'and a .reactancefea'ch divided intosectim a concentric rovided' with contacts arranged :illy, a controllingelement adaptto engage said contacts, and means for causing a quickbreak between said element and the contacts.

4. The combination with 'asingle-phase .b sourcefof current andaninductionmotor having a.threephasewinding, of means for starting thesaid motor comprisinga resistance and a reactance each divided intosections, a; con-troll g 'armtherei'br biased to the oii position, meanswhereby said controlling arm is "given a' quick breakfrom one sec:

, 7 tion toanother, ,and-a'no-volta'ge magnet for lioldingthe arminrunn'in 5.- In combination 1' wit source of current,- an inductionmptorhavmg position.

a'three-phas'e winding, tw.o devices of difierent irnpedaricefactors,means for connecting one terminal of the-motor to one portions of saidst'ep-by-step.

.a single-phase terminal ofthe source and connecting the other twoterminals of the winding through said two devices respectively to theother terminal of the source, and means for cutting said devices out ofcircuit step-by-stp.

6. In combination with a source of single-' phase current, an inductionmotor having a three-phase winding, EL'I'BSlStiLDCG, a reactance, meansfor connecting one terminal of t e motor winding to one terminal of thesource and connecting the other two terminals of, the motor windingthrough the resistance and reactance respectively to the other terminalof the source, and means for cutting out saidresistance and reactancestep-.by-etep. v

7. In combination with a source of singlephase current, an inductionmotor having a three-phase winding, a resistance, a reactance, means forconnecting one terminal of the motor winding to one terminal of thesource and connecting the other two terminals of the motor windingthrough the re sistance and reactance respectively to the other terminalof the source, and means for simultaneously cutting out proportionateresistance and reactance 8. In combination with a source of singlephasecurrent, aninduction motor having a polyphase winding, two devices ofdifferent impedance factors connected between one terminal .of' thesource and two different phase. terminals of said winding, and a switcharranged to cut ortions of said devices out of circuit and t on to breakthe circuit of one device and cut the remainder of 1 the other deviceout of circuit.

9. In combination with a source of singlephase current, an inductionmotor having a three-phase winding, a resistance connected one terminalof the source, a reactance' connected between a second terminal of saidwinding and the same terminal of the source, and a switch arranged toout portions of both resistance and reactance out of circuit, then tobreakthe circuit of one of these and cut the remainder of theother outof circuit.

In witness whereof, I have hereunto set my hand this 13th day ofFebruary, 1906.

HOWARD MAXWELL.

Witnesses:

BENJAMIN B. HULL, 'HELEN Onronn.

ctween one terminal of said winding and

